1. Field of the Invention
The invention relates generally to an assembly jig for pins for a power transmission chain, and more specifically to an assembly jig for pins for a power transmission chain suitable for a continuously variable transmission (CVT) of a vehicle such as an automobile.
2. Description of the Related Art
A power transmission chain suitable for a continuously variable transmission for an automobile includes a plurality of links, a plurality of first pins, and a plurality of second pins. Each link has front and rear insertion portions through which the pins are passed. Each first pin and a corresponding one of the second pins are aligned next to each other in the longitudinal direction of the links, and connect the links, aligned in the chain width direction, to each other such that the front insertion portion of one link corresponds to the rear insertion portion of another link. The first pins and the second pins move while being in rolling contact with respect to each other, so that the links are flexural with respect to each other in the chain length direction. Thus, the chain is able to shift from the straight state to the curved state. In a known power transmission chain, one of a first pin and a second pin is fixed to a front insertion portion of one link through press-fitting and is movably fitted in a rear insertion portion of another link, and the other of the first pin and the second pin is movably fitted in the front insertion portion of the one link and is fixed to the rear insertion portion of the other link through press-fitting. Japanese Patent Application Publication No. 2006-95583 describes a method of manufacturing such a power transmission chain. According to the method, a required number of pins are arranged with a predetermined pitch (at predetermined intervals) so as to vertically extend, and held in the same arrangement state as that when the pins are assembled into a chain. Then, links are sequentially press-fitted one by one to these pins from the lower ends.
Japanese Patent Application Publication No. 2006-95583 describes the following method of manufacturing a power transmission chain. According to the method, as shown in FIG. 7, while an assembly jig 41 for pins is rotated, each pair of pins 14, 15 is inserted into a corresponding one of pin insertion recesses 42 formed in the assembly jig 41 with a predetermined pitch. In this way, all the pins 14, 15 that are used in a chain 1 are arranged on the assembly jig 41 for pins, and held in the same arrangement state as that when the pins 14, 15 are assembled into the chain 1. Then, as shown in FIG. 8, links 11 used in the chain 1 are sequentially press-fitted to these pins 14, 15 by pressing jigs 45 such that the links 11 are laminated on top of each other in the chain width direction.
Further, a similar assembly jig for pins is described in, for example, U.S. Pat. No. 7,140,173.
The aforementioned conventional method of manufacturing a power transmission chain and the aforementioned conventional assembly jig for pins for a power transmission chain may cause the following inconvenience. That is, some pins that are loosely fitted in the assembly jig due to dimensional variations in manufacturing may topple down while the assembly jig for pins rotates. Accordingly, it is preferable to provide a device used to retain the pins. However, it is difficult to provide a retention device in such a manner that the retention device does not hinder press-fitting of the links by the pressing jigs. Therefore, retaining the pins with a compact and simple mechanism is a task that should be accomplished.